Router R1 sits at an Enterprise branch office, using the Internet for its only connectivity back
to the rest of the EnterprisE. Which of the following is not a benefit of using an IPsec tunnel
for packets sent through the Internet, between R1 and the rest of the
Enterprise?

A.
Privacy

B.
Authentication

C.
Allows using an IGP between R1 and the Enterprise

D.
Secure communications

Explanation:
IPsec tunnels make for more secure communications, including encryption and
authentication. However, it does not support IGP communications across the tunnel.